Lil Bub is a kitten-size cat with 2 million Instagram followers, a talk show, a stage production, an album and a book. The new study reveals the weird DNA behind what is often described as her magical appeal.

….

It helps to know what Lil Bub looks like to understand why they did this [examined her DNA]. The cat has a short snout, enormous green eyes and a pink tongue that hangs from her stunted jaw like an errant piece of bubble gum. She never developed teeth, and she stopped growing around four pounds. Each of her paws boasts an extra toe, for a total of 22. (Six on the front paws, five on the back.)

….

First, they compared her genome with that of a reference cat, then they focused on genes that control bodily functions. Finally, they asked a colleague who specializes in bone disorders which of those are known to cause osteopetrosis.

That led them to a mutation in a gene called RANK/TNFRSF11A, which has been found in about 15 humans and one mouse — all of whom, the researchers said, share physical similarities with Lil Bub. In X-rays, their bones look deformed and bright white, with little to no marrow cavity. The mouse, like Lil Bub, also was missing teeth, because they can’t erupt through bone that hardens too quickly. (Bub can eat just fine, and she runs and jumps thanks to a pulsed electromagnetic field therapy.)